Vehicles that utilize a battery as an energy source and a motor as a drive source, commonly referred to as electric vehicles, have become increasingly attractive in recent years due to their low pollution emissions, low noise, and reduced energy expense as compared to vehicles having internal combustion engines. The conventional electric vehicle utilizes axles upon which wheels and motors are mounted, along with power transmission devices such as a reduction gear and a differential gear. A drawback of such configurations is vehicle weight and power transmission efficiency, consequently increasing the vehicle's energy consumption and decreasing the vehicle's traveling distance between battery re-chargings (referred to as “range”). The relatively short range of electric vehicles has prevented them from finding widespread acceptance.
Some electric vehicles use a direct-drive type motor that is coupled to the wheels, eliminating the need for power transmission devices such as a reduction gear, a differential gear, a drive shaft, etc., thereby improving the efficiency of power transmission and decreasing the weight of the vehicle. These direct-drive type motor wheels, which directly transmit the motor torque to the wheels, fall under two types. A first type is configured such that the wheels are mechanically interlocked with the motor, while a second type is configured such that the motors are incorporated into the wheels.
Although the direct-drive motor represents an improvement in electric vehicle designs, the motor, power supply, and various ancillary elements, such as suspension components are typically individually attached to the vehicle. As a consequence, automobile designers are obliged to custom-develop powertrain and suspension configurations that are suitable for at most only a few vehicle designs. This results in more design labor and development testing for new vehicle designs than is desirable, since this effort drives up the cost of the vehicle and increases the amount of time needed to bring it to market. Once in service, the individually-attached devices can be expensive and labor-intensive to repair or replace in the event of a failure or damage.
Another drawback of current electric vehicles is that a considerable amount of space which could otherwise be utilized for cabin space is consumed by the drive train and suspension. It is desirable to increase the amount of cabin space in order to provide a more comfortable environment for the passengers and/or more cargo space.
Yet another drawback of current electric vehicle designs is that the batteries are typically located some distance from the motor or motors. Consequently, there can be a significant voltage drop in the power lines extending between the batteries and the drive motors, resulting in reduced vehicle performance and wasted energy.
There is a need for a powertrain and suspension system for electric vehicles that provides for efficient reconfiguration of vehicle designs, more cabin space, reduced repair cost, and reduced energy losses.